Pectin and its manufacture



Patented Jan. 2, 1940 UNITED STATE PECI'IN AND IT S MANUFACTURE PhilipBliss Myers,

W. Cowgill, Fairficld,

Scarsdale, N. Yuand William Com assignors vto Sardik Incorporated,Jersey City, N. J. a corporation of Delaware No Drawing.

This invention relates to pectin, and an object of the invention is toprotect pectin against decomposition or deterioration in the rawmaterial before extraction therefrom, during the extraction thereof fromthe raw material, and during its subsequent storage in commercial form.This application is a continuation in part ,of 'our application SerialNo. 34,218, filed August 1, 1935.

Although pectin occurs in most fruits and vegetables, it is usuallyobtained commercially from apple pomace which is the residue from thecider mill after the juice has been pressed from the apples, or fromalbedo which is the white part of citrus fruit. Pectin occurs in thesematerials in 5 the form of protopectin, an insoluble compound believedby many to be a combination of pectin and cellulose.

Inthe manufacture of pectin from pomace or other pectic material it isnecessary to liberate the pectinv from the insoluble protopectin bychemical means. The usual procedure is to hydrolyze the protopectin intoits constituents, pectin and cellulose, by heating the pomace withacidified water. The hydrolysis of the protopectin depends upon severalfactors, such as the length of time of the extracting operation,

the temperature and the hydrogen ion concentration of the extractingmedium. However, pectin itself is alsohydrolyzed-under theseconditions,so that heretofore in order to obtain the most satisfactoryresults it has been necessary to so regulate these three factors thatthe hydrolysis of the protopectin is as great as possible and thehydrolysis of the pectin is kept as small as pos- Such conditions ofextraction have not permitted obtaining both the highest yield and thehighest grade of pectin theoretically possible as the higher grades areonly obtained at the lower extracting temperatures, while the highestyields are only obtained at the higher extracting tem- 5, peratures.Thetrouble has resulted from the fact that although the hydrolysis ofthe protopectin to form pectin occursrapidly at elevated temperature's,the hydrolysis of the pectin itself, and hence its decomposition alsooccurs rapidly at elevated temperatures.

It will be seen that the amount and grade of pectin obtained in a givenoperation are variable. They jelly grade of the pectin is the number ,ofparts of sugar which one part'of pectin will jell under standardconditions. Heretofore, when a process had been. so carried on astoproduce the highest yield of pectin from a given raw material, thegrade ofthe pectin so produced has Application October .8, 1937, SerialNo. 167,936

8 Claims. (Cl. 260-210):

l been low. On the other hand, when the process of preparing pee in hasben so controlled as to obtain the higheEt, grade of pectin possible theyield has been to low for commercial success.

The value 'of an extraction process is deter- 5 mined by the number ofjelly units obtainable from a pectic material, such as apple pomace oralbedo. The term jelly-units is herein employed to designate the figureobtained by multiplying the jelly'grade of the pectin bythe percentage10 yield of pectin from the raw. material. From this definition it isquite obvious thatthe greater the amount of 'jelly units-obtainable froma definite Weight of pectin material the greater the amount of jellythat may bemade from the 15 resulting pectin. For example, it waspossible to obtain a 37.5% yield of pectin from a certain albedo in oneextraction. This pectin was 181 grade .50 that .the number of jellyunits obtained from the albedo was 67.9. Altering the conditions of theextraction and employing the same albedo, a 10% yield of a 472 gradepectin was obtained so that the numberof jelly units in this case wasonly 47 .2. The quantity of jelly that may be made from. the pectinextracted from a 25 definite weight of pectic material is directlyproportional to the number of jelly units obtained during theextraction. For example, in the two extractions cited above, where 67.9and 47.2 jelly units were'obtained, 11,312 and 7,867 pounds of a 30sugar jelly, respectivelyycould be made from the pectin extracted frompounds of albedo. In other words, 43.8% more jelly could be made fromthe 67.9 jelly unit extraction than from the extraction producing only47.2 jelly units. 'There- 35 fore the value of the pectin extracted from100 pounds of albedo would be approximately 43.8% greater in the case ofthe 67.9' jellyunit extraction. .7 I

Obviously, the extraction process which pro- 40 ducesthehighest numberofjelly units is the most economical one. Heretofore, so far as we knowno extraction process has been known that will produce jelly unitsapproaching the theoretical number contained in ajpectic material as 45it has been impossible to obtain maximum yields of high grade pectin. I

Aifurther object of this invention is to provide an improved pectinextraction process capable of producing a relatively large number ofjelly units. 50

These and other objects which will be apparent to those skilled in theart are attained by the present invention which comprises employing asuitablehydrolysis-inhibiting agent, as more fully set forthhereinafter, to prevent deterioration of 55 the pecan by hydrolyticaction either before, during or after extraction thereoiirom the rawmaterial.

Although we prefer to use glycerine as the hydrolysis-inhibiting agentbecause of its ready availability, "it will be apparent to those skilledin the art that other hydrolysis-inhibiting agents willbe efiective andcan be used in place of glycerine. We have 'found, .for example, thatthe derivatives of glycerine as well as any of the polyhydric alcoholsor their derivatives are suitmulated at a cider'mill it is hauled to akiln.

which may be a considerable distance fromthe mill, and there dried to amoisture content of approximately l0% in order to permit the pomacebeing kept as long as possible or until such time as it may be desiredfor pectin manuiacture. However, the raw material, even when properlydried, loses some of its jelly units it stored under normal atmosphericconditions. For this reason, it has always been customary to keep driedpomace in cold storage.

In applying the present invention to the protection of pectin in rawmaterial, we have found that if the raw material such, for example, aspomace from .the cider mill is soaked in a water solution of such ahydrolysis-inhibiting agent as glycerine, for example, for about onehour and again pressed, the jelly units in the pomace are approximately50% greater than otherwise and the pomace can be kept for several daysbefore drying'without any appreciable loss or, J'elly units. 'I'heglycerine'solution should contain from 3%to 4% glycerine. The soakingoperation .not only results in protection of the pectin but serves toremove a large percentage oi? soluble extraneous constituents, such assalts,

acid, sugars and the like, and thus produces a more concentrated pomacethan is normally obtained from a cider mill.

If desired, the poma'ce may be dried without the above Hescribe'dsoaking treatment, and

glycrine orother hydrolysis-inhibiting agent.

then sprayed on 'thedry poxnace as it issues from the kiln;

' Pomace containing glycerine, for example, can be kept at normaltemperatures for as long as a year 'or'more without appreciable loss ofjelly units.- It isnotnecessary .to keep it in cold storage, I

We have also found that the additionof a suit- 'able agent such asglycerine to the extracting" medium protects the pectin which isliberated during the extracting process, against hydrolysiseven inboiling solutions without noticeably delaying the hydrolysis of theprotopectin, so

that maximum yields of high grade pectin can be obtained. The additionoi' the glycerine permits extracting operations even at 100, 0., withacidified water, having pH values which produce maximum yields ofpectin. Ordinarily, under suchconditions the destruction of theliberated pectin so rapid that a large percentage 'of the jelly units islost.'- The amount of glycerine which itis necessary to add to. theextracting medium in order to protect the pectin during the extractingoperation willvary tromFa 25% to a 4.0% solution' depending upon theweight of the pectin which tracting medium not only permits the'use ofboiling temperatures, but also less acid or higher pH values may beemployed without any loss of jelly units. 'This is due to the iactthatthe hydrolysis-inhibiting agent protects the-pectin from destruction sothat the extraction period may be prolonged until maximum yields 61'pectin are obtained-resulting in a high yield of jelly units. Asaresult, excessive amounts of acid are not present in the pectin extractand therefore do not need to be subsequently eliminated.

the usual well kinow 'n I The variation in the amount of glycerlne or'the like necessary to protect the pectin during its extraction dependsupon the'length oi the extraction period, the pH of the extractingmedium and the temperature at which the operation is conducted. Ingeneral, the longer the extraction period, the lower the pH of theextr'acting medium and the higher the temperature, the more glycerine orother agent is required.

The pectin extract is then subjected to claritying treatment inaccordance with known methods, after which it usually contains from .25%.to 1.0% pectin. Such a dispersion is too weak for practical purposesand must be concentrated to a 3%, to 4% solution. Heretoiore thisconcentrating step has usually required expensive equipment includingvacuum evapora- 't'orsuto permit evaporation at a comparatively lowtemperature, such as 'C. or less, for the purpose of prot cting thepectin against the rapid hydrolysis pr need by higher temperatures.

We have found that the presence of glycerinc,

for example, in the concentrating 'oper on to be conducted in ordinarybpen kettles at 100 C. without apprejci able loss of'pectin due tohydrolysis. The glycerine may either be added to the pectin I extract,or, it the extracting operation'has been eflected' in the presence ofglycerine as itwill already be present.

We prefer to conduct theq concentrating o eration with the extract atapH value equal to '3.0 or above. It the pH valueis below ,3.0 theexcessive acidity should be neutralized by the addition of an alkali,such as ammonia or calcium carbonate. When the desired pH value isobtained, ii the glycerine is, not already pres'-' ent as-a result ofits employment in, the previous extracting step, it may be added in anamount equal to approximately one-half of the amount extract containsapproximately .5% pectin, glyc'- erine is added until thesolutioncontains approximately .25% glycerine by weight. With the ectin extractpermits the 1 above described 1 of the pectin present. Forexample,if,the pectin Heretofore the pectin concentrate, preparedwithout glycerine or other agent, has suife'red a noticeable loss injellying power after a stor! age of threeto four months, even thoughpacked in sterilized bottles, and such deterioration has occurred morerapidly in warm climates. Also, when a bottle of ordinary pectinconcentrateis a pectin concentrate made equal to approximately one-halfthe amount of pectin present may be stored for periods up to one year ormore without any appreciable loss in the jellying power of the pectin,and also that be open to the atmosphere such concentrate may for severaldays before any substantial loss of jellying power is app rent. I

Pectin concentrates-which do not already contain glycerine or otheragent may be protected against deteriorationby the addition of glycerineor the like thereto in an amount equal to approximately one-half theamount of pectin present. For example, it pectin, approximately-2.0%glycerine shouldbe added, assuming that the pilot the concentrate isat'3.0 or above. For concentrates having lower pH values, slightly moreglycerine should be added.

In commerce, in dry form as a powder prepared by precipitatingpectinlirom the liquidconcentrate, drying and grinding the precipitate,or, more recently, as flakes or a film prepared though conventional drypectin is more resistant to deteriorating influences than ordinarypectin concentrates as heretofore prepared, it, neverthe less,deteriorates with time, particularly if the pH value of the pectin iswithin the lolly-forming range, that is, equal to 3.5 or less. The lowerthe pH value the more rapidly does the pectin deteriorate, and thisdeterioration occurs even though the pectin contains no soluble salts orfree acid, although the deterioration is more rapid it such materialsare present with the pectin.

Inasmuch as the most important use for pectin is in the manufacture ofjelly, the making of which requires the mixing oi pectin, acid andsugar, it is highly desirable to combine dry pectin with an acid, such,for example as malic, tartaric or lactic acid so that the material canbe used to form jelly merely by combining with it a suitforms of pectin-Various tor jelly making have been not been particularly sucbecause insuch combinahydrolysis of the pectin able sugar solution. acidcombinations attempted, but have cessiul commercially tions the acidproduces so rapidly that within a short time the ilellyinui isappreciably power of the pectin in the mixture lowered and. may becompletely destroyed in a relatively short time: Y

We have found that'the presence or glycerine or the like in a drypectin-acid combination, either in powder or drolysis oi the pectin ofjellyinll P wer over times as much.as a year.-or more. The use ofglycerine, for example, for this purpose makes it possible for power.When glycerine or its ent, salts,'acid and moisture have substantiallyno destructive. eilect on the .We have amount oi-glycerine'togetherwith80% to 40% acid, soluble salts and the, like, over IOIII or time undersuch conditions that it absorbed iron 10% to 20% moisture, andthcresubstantiallynolclsiniellmm.

the above described process and containing glycerine or the like in anamount the concentrate contains 4.0%

pure pectin is usually distributed by drum drying. Al-

terial.

film form, inhibits the hy-; and protects it against los long periods0!. time, somepectin in the material and 'form tra the first-time to mixin, pectin without a loss of jellyingequivalentispresscribedhereinabove, and the concentrate is dried to produce dry pectin, it willnot be'necessary to add additional glycerine to the dry product as theglycerine present in the concentrate carries over in full amount duringthe drying operation and remains with the pectin protectingthe sameagainst deterioration both during andaiter the drying step; If thepectin concentrate has been prepared without the use of glycerine, thenthe glycerine should be added thereto prior to the drying operation. Itmay also be incorporated in dry pectin to produce the desired result.

It will be apparent that the present invention can be variously modifiedand adapted within the scope of the appended claims.

Weclaim: I

1. The methodoi protecting a pectic raw material against deteriorationvwhich consists in adding 1% to 4% glycerine thereto.

2. The method of protecting a pectic raw material against deteriorationwhichconsists in washing said raw-material in a 2% aqueous solution ofglycerine and then drying the material.

3. The method of protecting dried pectic raw materialtagainstdeterioration which consists in adding 3% to 4% glycerine thereto. 4.The method of preventing the loss. of jelly units from pectic rawmaterial which consists in soaking said materialin a 3% to 4% aqueoussolution of glycerine and then drying said ma- 5. Themethod ofpreventing'the loss of jelly units irom pectic raw material whichconsists in soaking said material in a 3% to 4% aqueous solution ofglycerine for. approximately one hour, 7

and then pressing said material and drying it.

6. The method of extracting pectin from pectic raw material whichconsists in adding the material to an acidified water, incorporatingglycerlne thereinflin an amount sufficient to prevent hydrolysis oi thepectin during the subsequent heat-.- ing operation, heating to hydrolyzethe proto-" pectin in the material and form pectin, and then separatingthe pectin thereirom.

'7. The method of extracting pectin irompectic raw material whichconsists in'adding the material to an acidified water,incorporatingglycer 'ine therein in an amount suificient to preventhydrolysis oi the pectin during the subsequent heating' operation,heating to hydrolyze the protop c o centhepectin extract, drying thepectin, and taining glycerine present in an amount equal toapproximately 50% 0! the pectin during the concentrating and dryingsteps. i

,8. The method which consists of incorporating glycerine'inpectintaining-rawmaterial, and

g subsequently extracting pectin irom said raw material andconcentrating the extract while maintaining glycerine present in amountequaif t s bst ially 50% ct the a ble pectin.

w ."oowenr-.

